You should not get exuberant on the mountains but rather focus on safety. The conditions can change at any time, so the behaviour on the spot often has to be flexibly adapted to them. The following methods and tactics should help you to minimize risks and avoid danger.
METHODS FOR RISK REDUCTION
In recent years, the assessment of avalanche danger has basically been defined in terms of slope inclination. Statistics have shown that this method is not tenable. For this reason, new approaches are needed to reduce the risk.
In recent years, the steepness of a slope in combination with the danger level has been considered a decisive factor in assessing the avalanche danger. However, every year there are avalanche incidents that should not have happened using this approach. According to statistics, 20 percent of all fatal accidents are within the green zone of the reduction method. Ben Reuter of the SLF and Chris Semmel of the VDBS have based their approach on the latest statistics and applied it to other factors. The 30 degree limit still applies - below 30 degrees there are no avalanches (taking into account the catchment areas). Nowadays we know that at avalanche warning levels 2, 3 and 4 snow slab avalanches have exactly the same steepness distribution. Snow slides from 30 degrees and most often at 38.7 degrees - regardless of the danger level. Also the catchment area (assessment radius) does not depend on the danger level, but on the snow cover.
The new scheme of Semmel and Reuter is: G -> K -> M R
Here, G stands for Recognize danger and assess the probability of its occurrence, K for Estimate consequences, M for Take action and R for Assess risk. This method can be used for route planning as well as for individual decisions. What is new is that the consequences of an avalanche are already assessed in the planning phase and are included in the entire planning process. This is because the avalanche risk is always made up of the triggering probability and the consequences.
The avalanche situation report is still the starting point of any planning. But more important than the warning level is the information on the avalanche problem. Is there currently an old or fresh snow problem? Nowadays the avalanche problems are named in all avalanche situation reports and visualized by symbols.
- What does the situation report say? Are there avalanche problems? Where are the danger spots? Does the avalanche report limit danger spots?
- Important from the hazard description: What additional information is given in the management report? - Triggering at low or high additional load? Possibility of remote or self-triggering?
- What is the weather like and what changes are there during the day - precipitation, wind with drifting snow, visibility, temperature?
- Is there any additional information on the snowpack and its structure? - Snow profiles, stability test?
Detect danger points
The 30 degree method is used to identify the danger spots and define checkpoints. For this purpose, all slopes above 30 degrees along and above the route are searched on the map, regardless of the danger level. If the slope is outside the core zone (danger spot mentioned in the situation report), it is assumed to be favourable. If remote triggering is not to be expected (not mentioned in the LLB and no old-snow/fresh-snow problem exists), can adjacent slopes above the planned route also be assumed to be favourable?
Estimate the triggering probability at the danger point. The avalanche report is broken down for the region (downscaling).
There is a form for this purpose, which serves as a checklist. This is used to compare the local conditions with those mentioned in the management report. (Checklist can be downloaded from the Internet at: projektberg.de) The aim here is to compare the Management Report with the actual conditions on site by asking the following questions
- How steep is the slope? The steeper the slope, the more dangerous, because the slope steepness correlates with the fracture initialization.
There are three classes: yellow 30-35 degrees, orange 35-40 degrees, red > 40 degrees.
- Are there any alarms? Is there snow cover information or tests? Which avalanche problem exists? Are the danger spots limited and where are they located?
Now try to answer the following four questions for each key point. Anything that cannot be answered during planning will be added or corrected during the tour.
- Can a snow slab be triggered here? (Weak layer present and disturbable, <1m depth)
- Is fracture propagation to be expected? (Fresh avalanches, boom, cracks, test results of the snow cover test)
- Are there other dangers? (Other persons above, fall, self-triggering, crevices)
- Are there any fresh tracks? Since in 90 percent of accidents the snow slab is triggered by the first person, tracks are not an absolute sign of safety, but they are another indication.
As described above, answer the four questions on the form again:
- How long is the slope at the key point? The bigger a slope, the longer the avalanche and energy (speed, burial depth).
- How much snow is in motion (avalanche size)? The wider and deeper a crack is expected to be, the deeper a burial will be and the smaller the chance of survival (chance of survival clearly correlates with the burial depth).
- Are there terrain traps such as demolitions, obstacles, ditches, that could cause mechanical injuries or increase the burial depth?
- Are safe collection points possible? The aim must be that no more than one person is in the danger zone, so that everyone else can step in as helpers.
Now it is time to think about measures to counter the problems that have been identified. For example, a possible initialization can be made less likely by relief distances. This is the case when the management report speaks of "major additional burden". This is because distances and individual driving reduce the load on the snowpack to "low". Or the consequences can be reduced by using safe collection points.
Are there alternatives to the key point (environment)? Are there alternative destinations?
Assessing the risk
Does the tour suit the prevailing conditions and me and the group? Is this the right tour for everyone I am touring with (number, ability, motivation)?
On the tour we will continue to work with the GKMR method until the individual slope is assessed.
The approach, like most theories and approaches to avalanches, is at first glance very complex. However, a closer look reveals that many of the points are taken up that experienced ski tourers have always been aware of. Semmel and Reuter have refined and systematised these thoughts. Studies have been carried out on all points, which prove the connections with the avalanche risk.
Text by Chris Semmel
state-certified mountain and ski guide - has been dealing with the avalanche problem for years